<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>循环</title>
</head>
<body>
        <script>
          var i = 0;
          var  arr=['10','20','30'];

          while (i < arr.length){
              console.log(arr[i]);
              i++
          }
        </script>
</body>
</html>